Abstract:

A thermal head includes heat generating parts and a conductive layer
having connecting parts electrically connected to ends of the heat
generating parts. The conductive layer has wiring parts whose
cross-sectional areas are smaller than cross-sectional areas of the
respective connecting parts in directions. The wiring parts has a first
upper layer and a second upper layer which have smaller widths in arrow
directions than widths of the respective connecting parts, as well as a
first lower layer and a second lower layer which have lengths not shorter
than the widths of the respective connecting parts and greater than the
widths of the respective upper layers. The respective upper layers and
the respective lower layers are arranged to overlap each other.

Claims:

1. A recording head comprising:a substrate;a plurality of heat generating
parts arranged on the substrate; anda conductive layer electrically
connected to each of the heat generating parts,wherein the conductive
layer includes a connecting part electrically connected to the heat
generating parts and a wiring part electrically connected to the
connecting part, the wiring part having a smaller cross-sectional area
along an arrangement direction of the heat generating parts, than a
cross-sectional area of the connecting part along the arrangement
direction of the heat generating parts, andthe wiring part includes a
first part having a smaller width in a plan view along the arrangement
direction of the heat generating parts, than a width of the connecting
part in a plan view along the arrangement direction of the heat
generating parts, and a second part located in such a way that at least
part thereof overlaps with the first part, the second part having a
greater width in a plan view along the arrangement direction of the heat
generating parts, than the width of the first part in the plan view of
the arrangement direction of the heat generating parts.

2. The recording head of claim 1, wherein an entirety of the first part is
located on the second part.

3. The recording head of claim 1, wherein the width of the second part in
the plan view is equal to or smaller than the width of the connecting
part in the plan view.

4. The recording head of claim 1, wherein the second part includes a first
layer and a second layer which is formed of a material different from a
material for the first layer and formed integrally with the first part.

5. The recording head of claim 1, wherein the heat generating part is
formed integrally with the second part.

6. The recording head of claim 1, wherein the first part includes a first
conducting path and a second conducting path which is electrically
parallel to the first conducting path.

7. The recording head of claim 6, wherein the second part extends between
the first conducting path and the second conducting path in the plan
view.

8. The recording head of claim 1, wherein the wiring part comprises a
plurality of the wiring parts,the conductive layer further includes a
common connecting part to which each of the plurality of the wiring parts
is connected, andthe second parts of the respective wiring parts are
connected to one another situated next thereto in the arrangement
direction of the heat generating parts, at ends thereof connected to the
common connecting part.

9. The recording head of claim 1, wherein the wiring part comprises a
plurality of the wiring parts,the conductive layer further includes a
common connecting part to which each of the plurality of the wiring parts
is connected, andthe common connecting part has a smaller thickness
between ends thereof connected to the wiring parts situated next to one
another in the arrangement direction of the heat generating parts, than a
thickness of a region of the end thereof connected to the first part of
the wiring part.

10. The recording head of claim 1, further comprising a plurality of
transmitting parts each having an end connected to the wiring
part,wherein the wiring part has a smaller cross-sectional area along the
arrangement direction of the heat generating parts at an end thereof
connected to the connecting part, than a cross-sectional area along the
arrangement direction of the heat generating parts at an end of the
connecting part connected to the heat generating part, and has a greater
cross-sectional area along the arrangement direction of the heat
generating parts at an end thereof connected to the transmitting part,
than the cross-sectional area along the arrangement direction of the heat
generating parts at the end of the connecting part connected to the heat
generating part, andthe transmitting part includes, at an end thereof
connected to the wiring part, a lower layer having a greater width in a
plan view than the width of the first part in the plan view, and an upper
layer located on the lower layer and having a width in a plan view almost
a same as the width of the first part in the plan view.

11. The recording head of claim 1, wherein the conductive layer includes a
first conductive layer connected to one end of the heat generating part
and a second conductive layer connected to another end of the heat
generating part, anda cross-sectional area of the wiring part in the
first conductive layer along the arrangement direction of the heat
generating parts, is smaller than a cross-sectional area of the wiring
part in the second conductive layer along the arrangement direction of
the heat generating parts.

12. A recording apparatus comprising the recording head of claim 1 and a
transport mechanism that transports a recording medium.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a recording head such as a thermal
head and an ink-jet head, which is used as a printing device in a
facsimile, a barcode printer, a video printer, a digital photo printer
etc., and a recording apparatus provided with the same.

BACKGROUND ART

[0002]There is a thermal printer including a thermal head in which a
plurality of heat generating parts are arranged and formed and a
transport mechanism transporting a recording medium to the heat
generating parts of the thermal head, and forming an image by
transferring the heat generated in each heat generating part to the
recording medium such as heat sensitive paper in accordance with a signal
input to the thermal head (see, for example, Patent Document 1). The heat
generating parts of the thermal head mounted on the thermal printer
structured as described above are electrically connected to a conductive
pattern, and are supplied with power according to an intended image via
the conductive pattern.

[0003]However, in the thermal head described above, the heat generated in
the heat generating parts is dissipated via the conductive pattern. As a
result, in the thermal head described above, sometimes the heat generated
in the heat generating parts is not transferred effectively to the
recording medium. To transfer the required amount of heat to the
recording medium in the thermal head described above, the amount of heat
generated in the heat generating parts has to be increased excessively,
resulting in a considerable amount of power consumption. Therefore, a
thermal head in which the width of a conductive pattern in a plan view
near a heat generating part is made narrow compared to other parts in
order to prevent dissipation via the conductive pattern has been
developed (see, for example, Patent Documents 2 and 3).

[0007]An object of the invention is to provide a recording head which can
enhance electrical reliability while making effective use of the heat
generated in a heat generating part, and a recording apparatus provided
with the recording head.

Solution to Problem

[0008]A recording head of the invention comprises a substrate, a plurality
of heat generating parts arranged on the substrate, and a conductive
layer electrically connected to each of the heat generating parts.

[0009]The conductive layer includes a connecting part and a wiring part.
The connecting part is electrically connected to the heat generating
part. The wiring part is electrically connected to the connecting part,
and has a smaller cross-sectional area along an arrangement direction of
the heat generating parts, than a cross-sectional area of the connecting
part along the arrangement direction of the heat generating parts.

[0010]The wiring part includes a first part and a second part. The first
part has a smaller width in a plan view along the arrangement direction
of the heat generating parts, than a width of the connecting part in a
plan view along the arrangement direction of the heat generating parts.
The second part is located in such a way as to overlap with the first
part, and has a greater width in a plan view along the arrangement
direction of the heat generating parts, than a width of the first part in
the plan view along the arrangement direction of the heat generating
parts.

[0011]The invention further comprises a recording apparatus provided with
the recording head described above and a transport mechanism that
transports a recording medium.

ADVANTAGEOUS EFFECTS OF INVENTION

[0012]A recording head of the invention includes a connecting part having
a conductive layer electrically connected to a heat generating part and a
wiring part whose cross-sectional area along the arrangement direction of
the heat generating parts is small compared to the connecting part. As a
result, in the recording head, the heat generated in the heat generating
parts is hard to be transferred to the wiring part. Consequently, in the
recording head, it is possible to reduce dissipation of the heat
generated in the heat generating parts via the wiring part. This makes it
possible to make effective use of the heat generated in the heat
generating parts.

[0013]The wiring part in the recording head includes a first part whose
width in a plan view is smaller than the width of the connecting part in
a plan view and a second part located in such a way as to overlap with
the first part and having a greater width in the plan view than the width
of the first part in the plan view. As a result, in the recording head,
even when cracks or the like appear in a region in which the first part
and the second part overlap, the region on which pressing force is likely
to act when the pressing force is exerted on an area near the heat
generating parts by a platen or the like, it is possible to ensure
predetermined electrical conduction in a region of the second part, the
region in which the second part lies off the first part in the plan view.
Consequently, in the recording head, it is possible to enhance electrical
reliability in the wiring part.

BRIEF DESCRIPTION OF DRAWINGS

[0014]FIG. 1 is a plan view showing a schematic structure of a thermal
head X1 which is an example of an embodiment of a recording head of the
invention.

[0015]FIG. 2A is a plan view of an enlarged main part of a base shown in
FIG. 1, and FIG. 2B is a sectional view taken on line IIb-IIb shown in
FIG. 2A.

[0016]FIG. 3A is a sectional view taken on line IIIa-IIIa shown in FIG.
2A, FIG. 3B is a sectional view taken on line IIIb-IIIB shown in FIG. 2A,
FIG. 3C is a sectional view taken on line IIIc-IIIc shown in FIG. 2A, and
FIG. 3D is a sectional view taken on line IIId-IIId shown in FIG. 2A.

[0017]FIG. 4 is a plan view showing a schematic structure of a thermal
head X2 which is another example of the embodiment of the recording head
of the invention.

[0018]FIG. 5 is a plan view of an enlarged main part of a base shown in
FIG. 4.

[0019]FIG. 4 is a sectional view taken on line VIa-VIa shown in FIG. 5,
FIG. 6B is a sectional view taken on line VIb-VIb shown in FIG. 5, FIG.
6C is a sectional view taken on line VIc-VIc shown in FIG. 5, and FIG. 6D
is a sectional view taken on line VId-VId shown in FIG. 5.

[0020]FIG. 7A is a sectional view taken on line VIIa-VIIa shown in FIG. 5,
FIG. 7B is a sectional view taken on line VIIb-VIIb shown in FIG. 5, FIG.
7C is a sectional view taken on line VIIc-VIIc shown in FIG. 5, and FIG.
7D is a sectional view taken on line VIId-VIId shown in FIG. 5.

[0021]FIG. 8A is a sectional view taken on line VIIIa-VIIIa shown in FIG.
5, and FIG. 8B is a sectional view taken on line VIIIb-VIIIb shown in
FIG. 5.

[0022]FIG. 9 is a sectional view taken on line IX-IX shown in FIG. 5.

[0023]FIG. 10 is an overall view showing a schematic structure of a
thermal printer which is an example of an embodiment of a recording
apparatus of the invention.

[0024]FIG. 11 is a diagram showing a modified example of a first
conductive layer of the thermal head shown in FIG. 1.

[0025]FIG. 12 is a diagram showing a modified example of the first
conductive layer of the thermal head shown in FIG. 1.

[0026]FIG. 13 is a diagram showing a modified example of a conductive
layer of the thermal head shown in FIG. 1.

[0027]FIG. 14A is a plan view showing a modified example of the conductive
layer of the thermal head shown in FIG. 1, and FIG. 14B is a sectional
view taken on line XIVb-XIVb shown in FIG. 14A.

[0028]FIG. 15 is a diagram showing a modified example of the first
conductive layer of the thermal head shown in FIG. 1.

[0029]FIG. 16 is a diagram showing a modified example of the first
conductive layer of the thermal head shown in FIG. 1.

REFERENCE SIGNS LIST

[0030]X1, X2 thermal head

[0031]Y Thermal printer

[0032]11 Substrate

[0033]12 Thermal storage layer

[0034]13 Resistor layer

[0035]131 Heat generating part

[0036]14 Conductive layer

[0037]141 First conductive layer

[0038]141a First upper layer

[0039]141b First lower layer

[0040]1411 First connecting part.

[0041]1412 First wiring part

[0042]1413A First transmitting part

[0043]142 Second conductive layer

[0044]142a Second upper layer

[0045]142b Second lower layer

[0046]1421 Second connecting part

[0047]1422 Second wiring part

[0048]1423 Common connecting part

[0049]30 Transport mechanism

[0050]P Recording medium

[0051]T Thickness of conductive layer

[0052]LH Length of heat generating part in plan view

[0053]WH Width of heat generating part in plan view

[0054]W11 Width of first connecting part in plan view

[0055]W11a Width of first lower layer in plan view in part
corresponding to first connecting part

[0056]W12a Width of first lower layer in plan view in part
corresponding to first wiring part

[0057]W11b Width of first upper layer in plan view in part
corresponding to first connecting part

[0058]W11b Width of first upper layer in plan view in part
corresponding to first wiring part

[0059]W21 Width of second connecting part in plan view

[0060]W21a Width of second lower layer in plan view in part
corresponding to first connecting part

[0061]W21b Width of second lower layer in plan view in part
corresponding to first wiring part

[0062]W22a Width of second upper layer in plan view in part
corresponding to first connecting part

[0063]W22b Width of second upper layer in plan view in part
corresponding to first wiring part

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment

[0064]A thermal head X1 shown in FIG. 1 includes a base 10, a driving IC
20, and an external connection member 21.

[0065]As shown in FIGS. 2A and 2B, the base 10 includes a substrate 11, a
thermal storage layer 12, a resistor layer 13, a conductive layer 14, and
a protective layer 15. Incidentally, in FIG. 2A, the protective layer 15
is omitted.

[0066]The substrate 11 has the function of supporting the thermal storage
layer 12, the resistor layer 13, the conductive layer 14, the protective
layer 15, and the driving IC 20. The substrate 11 is formed of an
electrical insulating material, for example, in a rectangular shape
extending in the directions of arrows D1 and D2 in a plan view. Here, the
"electrical insulating material" is a material that resists the flow of
electricity and has a resistivity of 1.0×1012 [Ωcm] or
more, for example. Examples of such an electrical insulating material
include ceramic such as alumina ceramic, a resin material such as
epoxy-based resin and silicon-based resin, a silicon material, and a
glass material. Alumina ceramic is the preferred material for the
substrate 11.

[0067]The thermal storage layer 12 has the function of temporarily storing
part of the heat generated in heat generating parts 131, which will be
described later, of the resistor layer 13. That is, the thermal storage
layer 12 improves the thermal response characteristics of the thermal
head X1 by shortening the time required to raise the temperature of the
heat generating parts 131. The thermal storage layer 12 is located on the
substrate 11, and is formed in the shape of a band extending in the
directions of arrows D1 and D2. The thermal storage layer 12 has a
virtually semielliptical cross-sectional shape in the orthogonal
direction orthogonal to the directions of arrows D1 and D2. Examples of
the material forming the thermal storage layer 12 include a material with
lower heat conductivity than the substrate 11. Examples of such a
material include a resin material such as epoxy-based resin and
polyimide-based resin and a glass material.

[0068]The resistor layer 13 is located on the thermal storage layer 12,
and is electrically connected to the conductive layer 14. Examples of the
material forming the resistor layer 13 include an electrical resistance
material with higher resistivity than the conductive layer 14. Examples
of the electrical resistance material include a TaN-based material, a
TaSiO-based material, a TaSiNO-based material, a TiSiO-based material, a
TiSiCO-based material, and a NbSiO-based material. The resistor layer 13
includes the heat generating parts 131 generating heat when a voltage is
applied from the conductive layer 14.

[0069]The heat generating parts 131 are configured to generate heat
ranging from 200° C. or more to 450° C. ox less, for
example, as a result of the voltage being applied from the conductive
layer 14. Above the thermal storage layer 12, the heat generating parts
131 are placed in a line in the main scanning directions (in the
longitudinal direction of the substrate 11) D1 and D2 in the thermal head
X1.

[0070]Each of the heat generating parts 131 is formed in a rectangular
shape in a plan view, the rectangular shape whose width WH in a plan
view along the main scanning directions D1 and D2 and length LH in a
plan view along the sub scanning direction directions (the lateral
direction of the substrate 11) D3 and D4 are almost the same. The width
WH in a plan view ranges from 5.2 [μm] or more to 76 [μm] or
less, for example. The length LH in a plan view ranges from 12
[μm] or more to 175 [μm] or less, for example. Here, the term
"almost the same" covers the common production error range, and an
example of the range is the range of error within 10 [%] with respect to
the average value of the dimensions of each part. Here, the term "in a
plan view" refers to looking in the direction of an arrow D6.

[0071]The conductive layer 14 has the function of applying a voltage to
the heat generating parts 131. The conductive layer 14 includes a first
conductive layer 141 located on the side along the direction of an arrow
D4 and a second conductive layer 142 located on the side along the
direction of an arrow D3. The thickness T of the conductive layer 14
(141, 142) is configured so as to be nearly uniform as a whole. For this
reason, the cross-sectional area in each part of the conductive layer 14
along the directions of arrows D1 and D2 depends on the width in a plan
view along the directions of arrows D1 and D2 in each part. Here, the
term "the cross-sectional area along the directions of arrows D1 and D2"
is the cross-sectional area in the thickness direction along the
directions of arrows D1 and D2; for example, is the area in a section (a
section in the thickness direction of the substrate 11) defined by arrows
D3 and D4-arrows D5 and D6.

[0072]The first conductive layer 141 includes a first connecting part 1411
and a first wiring part 1412.

[0073]The first connecting part 1411 has one end electrically connected to
one end of the heat generating part 131 on that side thereof facing in
the direction of an arrow D4. The first connecting part 1411 is so
configured that the width W11 thereof in a plan view along the
directions of arrows D1 and D2 is almost the same as the width WH of
the heat generating part 131 in a plan view (see FIGS. 2A and 3B).

[0074]The first wiring part 1412 has one end electrically connected to the
other end of the first connecting part 1411 and the other end
electrically connected to the driving IC 20. The first wiring part 1412
extends, in the direction of an arrow D4, from the central portion of the
first connecting part 1411 in the directions of arrows D1 and D2.
Moreover, the first wiring part 1412 is so configured that the
cross-sectional area along the directions of arrows D1 and D2 is smaller
than the cross-sectional area of the first connecting part 1411 along the
directions of arrows D1 and D2 (see FIGS. 2A and 3A).

[0075]The first conductive layer 141 also includes a first lower layer
141a and a first upper layer 141b, and part of the first lower layer 141a
lies off the first upper layer 141b in a plan view.

[0076]Although part of the first lower layer 141a is located on the
thermal storage layer 12, most of the first lower layer 141a is located
on the substrate 11. The first lower layer 141a is so configured that the
width W11a in a plan view along the directions of arrows D1 and D2
in a part corresponding to the first connecting part 1411 is almost the
same as the width W11 of the first connecting part 1411 in a plan
view. Moreover, the first lower layer 141a is so configured that the
width W12a in a plan view along the directions of arrows D1 and D2
in a part corresponding to the first wiring part 1412 is equal to or
smaller than the width W11 of the first connecting part 1411 in a
plan view (see FIGS. 2A, 3A, and 3B).

[0077]Examples of the material forming the first lower layer 141a include
a conductive material with lower electric conductivity and heat
conductivity than the material for the first upper layer 141b. Examples
of such a conductive material include a TaN-based material, a TaSiO-based
material, a TaSiNO-based material, a TiSiO-based material, a TiSiCO-based
material, and a NbSiO-based material.

[0078]An entirety of the first upper layer 141b is located on the first
lower layer 141a. When the entirety of the first upper layer 141b is
located on the first lower layer 141a, it is possible to increase the
area of contact of the first wiring part 1412 with the thermal storage
layer 12.

[0079]The first upper layer 141b is so configured that the width
W11b, in a plan view along the directions of arrows D1 and D2 in a
part corresponding to the first connecting part 1411 is almost the same
as the width W11 of the first connecting part 1411 in a plan view
(see FIGS. 2A and 3B). Moreover, the first upper layer 141b is so
configured that the width W12b in a plan view along the directions
of arrows D1 and D2 in a part corresponding to the first wiring part 1412
is smaller than the width W11 of the first connecting part 1411 in a
plan view and the width W12a of the first lower layer 141a in a plan
view (see FIGS. 2A, 3A, and 3B).

[0080]Examples of the material forming the first upper layer 141b include
a conductive material containing metal as a chief component. Examples of
such a conductive material include aluminum, gold, silver, copper, and an
alloy of these metals.

[0081]The second conductive layer 142 includes a second connecting part
1421, a second wiring part 1422, and a common connecting part 1423.

[0082]The second connecting part 1421 has one end electrically connected
to the other end of the heat generating part 131 on that side thereof
facing in the direction of an arrow D3. The second connecting part 1421
is so configured that the width W21 thereof in a plan view along the
directions of arrows D1 and D2 is almost the same as the width WH of
the heat generating part 131 in a plan view (see FIGS. 2A and 3C).

[0083]The second wiring part 1422 has one end electrically connected to
the other end of the second connecting part 1421, and extends in the
direction of an arrow D3 toward the common connecting part 1423 from the
central portion of the second connecting part 1421 in the directions of
arrows D1 and D2. The second wiring part 1422 is so configured that the
cross-sectional area along the directions of arrows D1 and D2 is smaller
than the cross-sectional area of the second connecting part 1421 along
the directions of arrows D1 and D2 (see FIGS. 2A and 3D).

[0084]The common connecting part 1423 is electrically connected to the
other end of the second wiring part 1422. The common connecting part 1423
is electrically connected to an unillustrated power source.

[0085]The second conductive layer 142 also includes a second lower layer
142a and a second upper layer 142b, and part of the second lower layer
142a lies off the second upper layer 142b in a plan view.

[0086]Although part of the second lower layer 142a is located on the
thermal storage layer 12, most of the second lower layer 142a is located
on the substrate 11. The second lower layer 142a is so configured that
the width W21a in a plan view along the directions of arrows D1 and
D2 in a part corresponding to the second connecting part 1421 is almost
the same as the width W21 of the second connecting part 1421 in a
plan view. Moreover, the second lower layer 142a is so configured that
the width W22a along the directions of arrows D1 and D2 in a part
corresponding to the second wiring part 1422 is equal to or smaller than
the width W21 of the second connecting part 1421 in a plan view (see
FIGS. 2A, 3C, and 3D).

[0087]As the material forming the second lower layer 142a, a conductive
material with lower electric conductivity and heat conductivity than the
material for the second upper layer 142b, for example, is used. Examples
of such a conductive material include a TaN-based material, a TaSiO-based
material, a TaSiNO-based material, a TiSiO-based material; a TiSiCO-based
material, and a NbSiO-based material.

[0088]An entirety of the second upper layer 142b is located on the second
lower layer 142a. When the entirety of the second upper layer 142b is
located on the second lower layer 142a, it is possible to increase the
area of contact of the second wiring part 1422 with the thermal storage
layer 12.

[0089]The second upper layer 142b is so configured that the width
W21b in a plan view along the directions of arrows D1 and D2 in a
part corresponding to the second connecting part 1421 is almost the same
as the width W21 of the second connecting part 1421 in a plan view
(see FIGS. 2A and 3C). Moreover, the second upper layer 142b is so
configured that the width W22b in a plan view along the directions
of arrows D1 and D2 in a part corresponding to the second wiring part
1422 is smaller than the width W21 of the second connecting part
1421 in a plan view and the width W22a of the second lower layer
142a in a plan view (see FIGS. 2A and 3D).

[0090]Preferably, the second upper layer 142b is so configured that the
width W22b in a plan view is greater than the width W12b of the
first upper layer 141b in a plan view.

[0091]Examples of the material forming the second upper layer 142b include
a conductive material containing metal as a chief component. Examples of
such a conductive material include aluminum, gold, silver, copper, and an
alloy of these metals.

[0092]The protective layer 15 has the function of protecting the heat
generating parts 131 and the conductive layer 14. Examples of the
material forming the protective layer 15 include an electrical insulating
material. Examples of such an electrical insulating material include
SiO2, a SiN-based material such as silicon nitride
(Si3N4), a SiNO-based material such as SIALON (Si.Al.O.N), and
a SiC-based material.

[0093]The driving IC 20 has the function of controlling a power supply
state of a plurality of heat generating parts 131. The driving IC 20 is
electrically connected to the conductive layer 14 and the external
connection member 21. The external connection member 21 has the function
of supplying an electrical signal for driving the heat generating parts
131. Examples of the external connection member 21 include flexible
printed circuits (Flexible Printed Circuits) and wiring substrates. When
such an external connection member 21 and the driving IC 20 are
connected, the driving IC 20 can make the heat generating parts 131
generate heat selectively based on the image information supplied via the
external connection member 21.

[0094]In the thermal head X1 described above, the first and second wiring
parts 1412 and 1422 in the conductive layer 14 are so configured that the
cross-sectional areas along the directions of arrows D1 and D2 are
smaller than those of the first and second connecting parts 1411 and
1421. Consequently, in the thermal head X1, the heat generated in the
heat generating parts 131 resists being conveyed to the wiring parts 1412
and 1422, making it possible to reduce dissipation of the heat generated
in the heat generating parts 131 in the wiring parts 1412 and 1422. This
allows the thermal head X1 to make effective use of the heat generated in
the heat generating parts 131.

[0095]The conductive layer 14 is so configured that the widths W12a
and W22a in a plan view in parts corresponding to the wiring parts
1412 and 1422 in the first and second lower layers 141a and 142a are
greater than the widths W12b and W22b in a plan view in parts
corresponding to the wiring parts 1412 and 1422 in the first and second
upper layers 141b and 142b. This makes it possible to ensure
predetermined electrical conduction in the lower layers 141a and 142a by
the lower layers 141a and 142a lying off the upper layers 141b and 142b
even when cracks or the like appear in regions in which the lower layers
141a and 142a and the upper layers 141b and 142b overlap, the regions on
which pressing force is likely to act when the pressing force is exerted
on an area near the heat generating parts 131 by a platen, for example,
while making effective use of the heat generated in the heat generating
parts 131 in the upper layers 141b and 142b. Therefore, in the thermal
head X1, it is possible to enhance electrical reliability in the wiring
parts 1412 and 1422 while making effective use of the heat generated in
the heat generating parts 131.

[0096]In the conductive layer 14, since the upper layers 141b and 142b are
located on the lower layers 141a and 142a, the areas of contact of the
first and second wiring parts 1412 and 1422 with the thermal storage
layer 12 are satisfactorily secured. As a result, in the thermal head X1,
it is possible to enhance the adhesion of the wiring parts 1412 and 1422
to the thermal storage layer 12. Therefore, in the thermal head X1, it is
possible to reduce the possibility that the first wiring part 1412 or the
second wiring part 1422 falls off the thermal storage layer 12, thereby
enhancing electrical reliability.

Second Embodiment

[0097]A thermal head X2 shown in FIG. 4 differs from the thermal head X1
described earlier with reference to FIGS. 1 to 3 in that a base 10A with
a conductive layer 14A (see FIGS. 5 to 9) having a different structure is
adopted. On the other hand, the structure of the thermal head X2 is the
same as that of the thermal head X1 except for the base 10A (the
conductive layer 14A) of the thermal head X2.

[0098]As shown in FIGS. 5, 8A, 8B, and 9, the conductive layer 14A
includes a first conductive layer 141A and a second conductive layer
142A. Incidentally, in FIG. 5, the protective layer 15 is omitted.

[0099]The first conductive layer 141A includes a first connecting part
1411A, a first wiring part 1412A, and a first transmitting part 1413A.

[0100]The first connecting part 1411A has one end electrically connected
to one end of the heat generating part 131 on that side thereof facing in
the direction of an arrow D4. The first connecting part 1411A is so
configured that the width W11A in a plan view along the directions
of arrows D1 and D2 is almost the same as the width WH of the heat
generating part 131 in a plan view.

[0101]The first wiring part 1412A has one end electrically connected to
the other end of the first connecting part 1411A and the other end
electrically connected to one end of the first transmitting part 1413A.
The first wiring part 1412A is so configured that, at the end connected
to the first connecting part 1411A, the cross-sectional area along the
directions of arrows D1 and D2 is smaller than the cross-sectional area
of the first connecting part 1411A along the directions of arrows D1 and
D2. On the other hand, the first wiring part 1412A is so configured that
the cross-sectional area (see FIG. 6B) along the directions of arrows D1
and D2 at the end connected to the first transmitting part 1413A is
greater than the cross-sectional area along the directions of arrows D1
and D2 at the end connected to the first connecting part 1411A and the
cross-sectional area (see FIG. 6D) in the first connecting part 1411A
along the directions of arrows D1 and D2.

[0102]The first transmitting part 1413A has one end electrically connected
to the other end of the first wiring part 1412A and the other end
electrically connected to the driving IC 20. The cross-sectional area
(see FIG. 6A) of the first transmitting part 1413A along the directions
of arrows D1 and D2 is greater than the cross-sectional areas of the
first wiring part 1412A and the first connecting part 1411A along the
directions of arrows D1 and D2.

[0103]The first conductive layer 141A also includes a first lower layer
141Aa, a first upper layer 141Ab, and a first middle layer 141Ac, and
part of the first lower layer 141Aa lies off the first upper layer 141Ab
in a plan view.

[0104]Although part of the first lower layer 141Aa is located on the
thermal storage layer 12, most of the first lower layer 141Aa is located
on the substrate 11. The first lower layer 141Aa is so configured that
the width W11Aa in a plan view along the directions of arrows D1 and
D2 in a part corresponding to the first connecting part 1411A is almost
the same as the width W11A of the first connecting part 1411A in a
plan view (see FIGS. 5 and 6D). The first lower layer 141Aa is so
configured that the width W12Aa in a plan view along the directions
of arrows D1 and D2 in a part corresponding to the first wiring part
1412A is equal to or smaller than the width W11A of the first
connecting part 1411A in a plan view (see FIGS. 5, 6C, and 6D). The first
lower layer 141Aa is so configured that the width W13Aa in a plan
view along the directions of arrows D1 and D2 in the first transmitting
part 1413A is almost the same as the width W11A of the first
connecting part 1411 in a plan view (see FIGS. 5, 6A, and 60).

[0105]Examples of the material forming the first lower layer 141Aa include
a conductive material with lower electric conductivity and heat
conductivity than the material for the first upper layer 141Ab. Examples
of such a conductive material include a TaN-based material, a TaSiO-based
material, a TaSiNO-based material, a TiSiO-based material, a TiSiCO-based
material, and a NbSiO-based material.

[0106]An entirety of the first upper layer 141Ab is located on the first
lower layer 141Aa. The first upper layer 141Ab is made uniform in
thickness as a whole, and is so configured that the thickness T11A,
the thickness T12A, and the thickness T13A in the first
connecting part 1411A, the first wiring part 1412A, and the first
transmitting part 1413A, respectively, are almost the same (see FIGS. 6A
to 6D, and 9).

[0107]The first upper layer 141Ab is so configured that the width
W11Aa, in a plan view along the directions of arrows D1 and D2 in
the first connecting part 1411A is almost the same as the width W11A
of the first connecting part 1411A in a plan view (see FIG. 6D). The
first upper layer 141Ab is so configured that the width W12Ab in a
plan view along the directions of arrows D1 and D2 in the first wiring
part 1412A is equal to or smaller than the width W11A of the first
connecting part 1411A in a plan view and the width W12Aa of the
first lower layer 141Aa in a plan view (see FIGS. 5, 6C, and 6D). As a
result, in the first wiring part 1412A, the first lower conductor 141Aa
lies off the first upper conductor 141Ab. In addition, the first upper
layer 141Ab is so configured that the width W13Ab in a plan view
along the directions of arrows D1 and D2 in the first transmitting part
1413A is almost the same as the width W11 of the first connecting
part 1411A in a plan view (see FIGS. 5, 6A, and 6D).

[0108]The width W13Ab of the first upper layer 141Ab in the first
transmitting part 1413A is so configured as to become longer with
distance from the end connected to the first wiring part 1412A in the
direction of an arrow D4 (with distance from the first wiring part 1412A)
while it is in a certain area away from the first wiring part 1412A.

[0109]Examples of the material forming the first upper layer 141Ab include
a conductive material containing metal as a chief component. Examples of
such a conductive material include aluminum, gold, silver, copper, and an
alloy of these metals.

[0110]The first middle layer 141Ac is located between the first lower
layer 141Aa and the first upper layer 141Ab in a part corresponding to
the first transmitting part 1413A, and does not present in parts
corresponding to the first connecting part 1411A and the first wiring
part 1412A. Unlike the first transmitting part 1413A, the width
W13Ac of the first middle layer 141Ac in a plan view along the
directions of arrows D1 and D2 is uniform, and is so configured as to be
almost the same as the width W13Aa of the first lower layer 141Aa in
a plan view. As a result, the first middle layer 141A lies off the first
upper layer 141Ab in a region from the end connected to the first wiring
part 1412A until the width W13Ab in a plan view in a part
corresponding to the first transmitting part 1413A in the first upper
layer 141Ab becomes almost the same as the width W11A of the first
connecting part 1411A in a plan view. The above region 1413Aa in which
the first middle layer 141Ac lies off the first upper layer 141Ab becomes
thin, in at least part thereof, in the direction of an arrow D3, and is
thinner than other regions. Preferably, the region 1413Aa has a low
degree of surface roughness compared to the first upper layer 141Ab.
Here, the "surface roughness" is, for example, the surface roughness
specified in the Japanese Industrial Standards B0601:2001.

[0111]Examples of the material forming the first middle layer 141Ac
include aluminum, gold, silver, copper, and an alloy of these metals.

[0112]The second conductive layer 142A includes a second connecting part
1421A, a second wiring part 1422A, and a common connecting part 1423A.

[0113]The second connecting part 1421A has one end electrically connected
to the other end of the heat generating part 131 on that side thereof
facing in the direction of an arrow D3. The second connecting part 1421A
is so configured that the width W21A in a plan view along the
directions of arrows D1 and D2 is almost the same as the width WH of
the heat generating part 131 in a plan view.

[0114]The second wiring part 1422A has one end electrically connected to
the other end of the second connecting part 1421A. The second wiring part
1422A is so configured that the cross-sectional area along the directions
of arrows D1 and D2 is smaller than the cross-sectional area of the
second connecting part 1421A along the directions of arrows D1 and D2.

[0115]The common connecting part 1423A electrically connects the second
wiring parts 1422A with each other, and is electrically connected to an
unillustrated power source.

[0116]The second conductive layer 142A also includes a second lower layer
142Aa, a second upper layer 142Ab, and a second middle layer 142Ac, and
part of the second lower layer 142Aa lies off the first upper layer 142Ab
in a plan view.

[0117]Although part of the second lower layer 142Aa is located on the
thermal storage layer 12, most of the second lower layer 142Aa is located
on the substrate 11. The width W21Aa in a plan view along the
directions of arrows D1 and D2 in a part corresponding to the second
connecting part 1421A is so configured as to be almost the same as the
width W21A of the second connecting part 1421A in a plan view. The
second lower layer 142Aa is so configured that the width W22Aa in a
plan view along the directions of arrows D1 and D2 in the second wiring
part 1422A is equal to or smaller than the width W21A of the second
connecting part 1421A in a plan view.

[0118]At the end of the second wiring part 1422A, the end connected to the
common connecting part 1423A, the second lower layer 142Aa is connected
to another second wiring part 1422A situated next thereto in the
directions of arrows D1 and D2.

[0119]As the material forming the second lower layer 142Aa, a conductive
material with lower electric conductivity and heat conductivity than the
material for the second upper layer 142Ab, for example, is used. Examples
of such a conductive material include a TaN-based material, a TaSiO-based
material, a TaSiNO-based material, a TiSiO-based material, a TiSiCO-based
material, and a NbSiO-based material.

[0120]An entirety of the second upper layer 142Ab is located on the second
lower layer 142Aa. The second upper layer 142Ab is made uniform in
thickness as a whole, and is so configured that the thickness T21A,
the thickness T22A, and the thickness T23A in the second
connecting part 1421A, the second wiring part 1422A, and the common
connecting part 1421A, respectively, are almost the same (see FIGS. 7A to
7D, and 8B).

[0121]The second upper layer 142Ab is so configured that the width
W21Ab in a plan view along the directions of arrows D1 and D2 in a
part corresponding to the second connecting part 1421A is almost the same
as the width W21A of the second connecting part 1421A in a plan view
(see FIGS. 5 and 7A). The second upper layer 142Ab is so configured that
the width W22Ab in a plan view along the directions of arrows D1 and
D2 in a part corresponding to the second wiring part 1422A is smaller
than the width W21A of the second connecting part 1421A in a plan
view and the width W22Aa in a plan view in the second wiring part
1422A of the second lower layer 142Aa (see FIGS. 5, 7A, and 7B). As a
result, in the second wiring part 1422A, the second lower conductor 142Aa
lies off the second upper conductor 142Ab.

[0122]Preferably, the second upper layer 142Ab is so configured that the
width W22Ab in a plan view is greater than the width W12Ab of
the first upper layer 141Ab in a plan view.

[0123]In addition, the second upper layer 142Ab is so configured that the
width W23Ab in a plan view along the directions of arrows D1 and D2
in a part corresponding to the common connecting part 1423A becomes
longer with distance from the end connected to the second wiring part.
1422A in the direction of an arrow D3 (with distance from the second
wiring part 1422A) while it is in a certain area away from the second
wiring part 1422A.

[0124]Examples of the material forming the second upper layer 142Ab
include a conductive material containing metal as a chief component.
Examples of such a conductive material include aluminum, gold, silver,
copper, and an alloy of these metals.

[0125]The second middle layer 142Ac is located between the second lower
layer 142Aa and the first upper layer 141Ab in a part corresponding to
the second common connecting part 1423A, and does not present in parts
corresponding to the second connecting part 1421A and the second wiring
part 1422A. An end of the second middle layer 142Ac, the end facing in
the direction of an arrow D4 in the common connecting part 1423A, lies
along the directions of arrows D1 and D2. As a result, in this
embodiment, the second middle layer 142Ac lies off the second upper layer
142Ab in a region until the ends of the common connecting part 1423A, the
ends connected to the second wiring parts 1422A, are connected to each
other in the second upper layer 142Ab. Moreover, the above region 1423Aa
in which the second middle layer 142Ac lies off the second upper layer
142Ab is thinner than other regions such as the second wiring part 1422A
in the second upper layer 142Ab. Furthermore, the region 1423Aa has a low
degree of surface roughness compared to the second upper layer 142Ab.
Also, the region 1423Aa has a larger area in a plan view compared to the
region 1413Aa. In addition, in this embodiment, part of the second middle
layer 142Ac located between the regions 1423Aa is so configured as to
become thin in the direction of an arrow D4.

[0126]Examples of the material forming the second middle layer 142Ac
include aluminum, gold, silver, copper, and an alloy of these metals.

[0127]In the thermal head X2, a plurality of second wiring parts 1422A are
provided, and the second conductive layer 142A further includes the
common connecting part 1423A connected to the plurality of second wiring
parts 1422A. On the other hand, at the end connected to the common
connecting parts 1423A, the second lower layer 142A of the second wiring
part 1422A and the second lower layer 142Aa of the second wiring part
1422A situated next thereto in the directions of arrows D1 and D2 are
connected to each other. This makes it possible to reduce a difference in
level in a region in which the second wiring part 1422A and the common
connecting part 1423A are connected. In the thermal head X2, it is
possible to form the protective layer 15 satisfactorily even when the
protective layer 15 is provided in such a way as to lie astride a
plurality of second wiring parts 1422A and the common connecting part
1423A. Consequently, in the thermal head X2, it is possible to protect
the heat generating parts 131 and the conductive layer 14 satisfactorily.

[0128]Furthermore, in the thermal head X2, the thickness in the end at
which the common connecting part 1423A is connected to the second wiring
part 1422A is smaller than the thickness of a region in which the common
connecting part 1423A is connected to the second wiring part 1422A in the
second upper layer 142Ab. As a result, it is possible to reduce a
difference in level in a region in which the second wiring part 1422A and
the common connecting part 1423A are connected. Consequently, in the
thermal head X2, it is possible to form the protective layer 15
satisfactorily even when, for example, the protective layer 15 is
provided so as to lie astride a plurality of second wiring parts 1422A
and the common connecting part 1423A. Therefore, in the thermal head X2,
it is possible to protect the heat generating parts 131 and the
conductive layer 14 satisfactorily.

[0129]The thermal head X2 further includes a plurality of first
transmitting parts 1413A each having one end connected to the other end
of the first wiring part 1412A. The cross-sectional area of the first
wiring part 1412A along the directions of arrows D1 and D2 at the end
connected to the first connecting part 1411A is smaller than the
cross-sectional area along the directions of arrows D1 and D2 at the end
of the first connecting part 1411A, the end connected to the heat
generating part 131, and the cross-sectional area thereof along the
directions of arrows D1 and D2 at the end connected to the first
transmitting part 1413A is greater than the cross-sectional area along
the directions of arrows D1 and D2 at the end of the first connecting
part 1413A, the end connected to the heat generating part 131. The first
transmitting part 1413A includes, at the end connected to the first
wiring part 1312A, the first lower layer 141Aa having the width
W13Aa in a plan view, the width W13Aa greater than the width
W12a in a plan view in a part corresponding to the first wiring part
1412A, and the first upper layer 141Ab located on the first lower layer
141Aa and having the width W13Ab in a plan view, the width
W13Ab which is almost the same as the width W12Ab in a plan
view in the first wiring part 1412A. Consequently, in the thermal head
X2, it is possible to reduce a difference in level in a region in which
the first wiring part 1412A and the first transmitting part 1413A are
connected, making it possible to form the protective layer 15
satisfactorily even when, for example, the protective layer 15 is
provided so as to lie astride a plurality of first wiring parts 1412A and
first transmitting parts 1413A. Therefore, in the thermal head X2, it is
possible to protect the heat generating parts 131 and the conductive
layer 14 satisfactorily.

[0130]In the thermal head X2, since, in the second conductive layer 142A,
the region 1423Aa has a low degree of surface roughness compared to the
surface roughness of the second upper layer 142Aa, it is possible to
reduce the degree of surface roughness of the protective layer 15
provided on the second upper layer 142Aa. Consequently, in the thermal
head X2, it is possible to reduce the friction on the region 1423Aa
located at the corner where pressing force becomes relatively great when
a recording medium, for example, is pressed against the thermal head X2,
and slide the recording medium satisfactorily. As a result, in the
thermal head X2, it is possible to transport the recording medium
satisfactorily, and reduce the possibility that the residues of the
recording medium adhere to the region 1423A located at the corner.

[0131]In the thermal head X2, since, in the first conductive layer 141A,
the region 1413Aa has a low degree of surface roughness compared to the
surface roughness of the first upper layer 141Aa, it is possible to
reduce the degree of surface roughness of the protective layer 15
provided on the first upper layer 141Aa. Consequently, in the thermal
head X2, it is possible to reduce the friction on the region 1413Aa
located at the corner where pressing force becomes relatively great when
a recording medium, for example, is pressed against the thermal head X2,
and slide the recording medium satisfactorily. As a result, in the
thermal head X2, it is possible to transport the recording medium
satisfactorily, and reduce the possibility that the residues of the
recording medium adhere to the region 1413A located at the corner.

[0132]In the thermal head X2, since the area of the region 1423Aa is
greater than the area of the region 1413Aa in width in a plan view, even
when, for example, a recording medium is transported, while being slid,
in the direction of an arrow D3, it is possible to reduce the friction
satisfactorily on the region 1413Aa extending in the directions of arrows
D1 and D2, the directions intersecting with the direction of
transportation.

[0133]<Printer>

[0134]FIG. 10 is an overall view showing a schematic structure of a
thermal printer Y according to this embodiment.

[0135]The thermal printer Y includes the thermal head X1, a transport
mechanism 30, and driving means 40, and performs printing on a recording
medium P transported in the direction of an arrow D3.

[0136]Incidentally, in this embodiment, the thermal head X1 is adopted as
a thermal head; however, the thermal head X2 may be adopted in place of
the thermal head X1.

[0137]Here, examples of the recording medium P include thermal recording
paper or a thermal film having a surface whose density varies by the
application of heat and a medium forming an image by transferring an ink
component of an ink film, the ink component melted by heat conduction, to
transfer paper.

[0138]The transport mechanism 30 has the function of bringing the
recording medium P into contact with the heat generating parts 131 of the
thermal head X1 while transporting the recording medium P in the
direction of an arrow D3. The transport mechanism 30 includes a platen 31
and transportation rollers 32, 33, 34, and 35.

[0139]The platen 31 has the function of pressing the recording medium P
against the heat generating parts 131. The platen 31 is rotatably
supported while being in contact with a part of the protective layer 15,
the part located above the heat generating parts 131. The platen 31 has a
structure made up of a cylindrical base having an outer surface covered
with an elastic member. The base is made of metal such as stainless
steel. The elastic member is made of butadiene rubber having a thickness
ranging from 3 [mm] or more to 15 [mm] or less, for example.

[0140]The transportation rollers 32, 33, 34, and 35 have the function of
transporting the recording medium P. That is, the transportation rollers
32, 33, 34, and 35 feed the recording medium P into the space between the
heat generating parts 131 of the thermal head X1 and the platen 31, and
pull the recording medium P out of the space between the heat generating
parts 131 of the thermal head X1 and the platen 31. These transportation
rollers 32, 33, 34, and 35 may be formed of a metal cylindrical member,
for example, or, as is the case with the platen 31, may have a structure
made up of a cylindrical base having an outer surface covered with an
elastic member, for example.

[0141]The driving means 40 has the function of supplying image information
to the driving IC 20. That is, the driving means 40 supplies the image
information for selectively driving the heat generating parts 131 to the
driving IC 20 via the external connection member 21.

[0142]Since the thermal printer Y is provided with the thermal head X1,
the thermal printer Y can enjoy the effects achieved by the thermal head
X1. In other words, the thermal printer Y can enhance electrical
reliability while making effective use of the heat generated in the heat
generating parts 131.

[0143]Moreover, the thermal head X1 is so configured that the
cross-sectional area of the first wiring part 1412 is smaller than the
cross-sectional area of the second wiring part 1422. As a result, in the
thermal head X1, it is possible to shift the position of a heat spot of
the thermal head X1 from the center of the heat generating part 131 in
the direction of an arrow D4, for example. Consequently, in the thermal
printer Y, even when transfer is performed by pressing, as the recording
medium P, an ink ribbon and plain paper, for example, against the heat
generating parts 131, it is possible to perform transfer on the plain
paper after melting the ink adequately by shifting the heat spot in the
direction of an arrow D4 from the position in which the greatest pressing
force is exerted by the platen 31. This eventually makes it possible to
form an image satisfactorily.

[0144]While specific embodiments of the invention have been described, the
invention is not limited to these embodiments, and various changes can be
made therein without departing from the gist of the invention.

[0145]The base 10 may be used as an ink-jet head provided with a top plate
with holes, for example. When the base 10 is used as the ink-jet head, it
is possible to ensure electrical reliability adequately even when
pressure associated with a shot of an ink or fluid pressure of an ink is
applied.

[0146]As for the conductive layer 14, for example, the first lower layer
141a and the first upper layer 141b may be formed of the same formation
material, or the second lower layer 142a and the second upper layer 142b
may be formed of the same formation material.

[0147]As shown in FIG. 11A, in the conductive layer 14, a conductive layer
14B, for example, may include an electrode 144B electrically connected to
the driving IC 20, an electrode 145B electrically connecting two heat
generating parts 131, and an electrode 146B supplying power to two heat
generating parts 131. Moreover, as shown in FIG. 11B, a conductive layer
14C may include an electrode 144C electrically connected to the driving
IC 20, an electrode 145C electrically connecting two heat generating
parts 131, and an electrode 146C supplying power to two heat generating
parts 131.

[0148]As shown in FIG. 12A, the first conductive layer 141 may be so
configured that a first lower layer 141Da includes a first layer
141Da1 and a second layer 141Db2 formed of a formation material
which is different from the material for the first layer 141Da1, the
second layer 141Db2 formed integrally with a first upper layer
141Db. With such a structure, it is possible to make greater the area of
contact between the parts formed of different materials, resulting in an
increase in adhesion between the parts formed of different materials in
the first wiring part. Therefore, in the thermal head with such a
structure, it is possible to reduce the separation between the parts
formed of different materials in the first wiring part, and thereby
enhance electrical reliability. Moreover, such a structure may be adopted
in the second conductive layer.

[0149]As shown in FIG. 12B, a first lower layer 141Ea and a first upper
layer 141Eb may be formed integrally by using a plurality of constituent
materials. Also with such a structure, it is possible to make greater the
area of contact of each constituent material. This makes it possible to
enhance the adhesion of the first lower layer 141Ea to the first upper
layer 141Eb, and enhance electrical reliability. Moreover, such a
structure may be adopted in the second conductive layer.

[0150]As shown in FIG. 13, the width W12b of the first upper layer
141b in a plan view may be so configured that the width W12Fb of a
first upper layer 141Fb in a plan view is greater than the width
W12Fa of a second lower layer 141Fa in a plan view.

[0151]Incidentally, the base 10 with such a structure can be formed by,
for example, laying protective layers 15Fa and 15Fb, forming a resin
layer in the first lower layer 141Fa, or providing the first lower layer
141Fa with electrical insulation.

[0152]The conductive layer 14 in accordance with the embodiments is so
configured that the first conductive layer 141 includes the first lower
layer 141a and the first upper layer 141a and the second conductive layer
142 includes the second lower layer 142a and the second upper layer 142b;
however, the structure is not limited thereto. Three or more electrodes
may be disposed in such a way that they overlap one another.

[0153]As shown in FIG. 14, the first conductive layer 141 and the second
conductive layer 142 may be so configured that a first upper layer 141Gb
and a second upper layer 142Gb include first conducting paths 141Gb1
and 142Gb1, respectively, and second conducting paths 141Gb2
and 142Gb2, respectively, which are electrically parallel to the
first conducting paths 141Gb1 and 142Gb1.

[0154]With such a structure, even when any one of the first conducting
paths 141Gb1 and 142Gb1 or any one of the second conducting
paths 141Gb2 and 142Gb2 is cut off, it is possible to ensure
predetermined electrical conduction by the remaining one conducting path.
Thus, this structure is suitable for enhancing electrical reliability in
the wiring part.

[0155]When lower layers 141Ga and 142Ga extend between the first
conducting paths 141Gb1 and 142Gb1 and the second conducting
paths 141Gb2 and 142Gb2 in a plan view, there is no need to
provide regions of the lower layers 141Gb and 142Gb, the regions whose
widths in a plan view are greater than those of the upper layers 141Ga
and 142Ga, outside the upper layers 141Ga and 142Ga. This makes it
possible to narrow the pitch of the heat generating parts 131. In such a
case, the width in a plan view in a first wiring part 1412G and a second
wiring part 1422G is the sum of the widths of the first conducting paths
141Gb1 and 142Gb1 and the second conducting paths 141Gb2
and 142Gb2 in a plan view in the first wiring part 1412G and the
second wiring part 1422G.

[0156]In the thermal head X1, for example, the resistor layer 13 may be
formed integrally with at least one of the first lower layer 141a and the
second lower layer 142a. With such a structure, it is possible to connect
the lower layers 141b and 142b in the heat generating part 131 and the
conductive layer 14 electrically satisfactorily. Thus, this structure is
suitable for enhancing electrical reliability.

[0157]As shown in FIG. 15, the first and second conductor layers 141 and
142 in the thermal head X1 may be so configured that the dimensions in
the first and second connecting parts 1411 and 1421 in the directions of
arrows D3 and D4 are greater than the dimensions in the first and second
wiring parts 1412 and 1422 in the directions of arrows D3 and D4.

[0158]As shown in FIG. 16, the first and second conductor layers 141 and
142 in the thermal head XI may be so configured that the widths in a plan
view in the first and second wiring parts 1412 and 1422 are smaller than
the widths W11 and W21 in a plan view in the first and second
connecting parts 1411 and 1421. In this case, the first and second upper
layers 141b and 142b in the conductor layer 14 are so configured that the
widths W12b and W22b in a plan view in parts corresponding to
the wiring parts 1412 and 1422 are smaller than the widths W12a and
W22a of the first and second lower layers 141a and 142a in a plan
view.